A multiple disk brake of the so called hydraulically relieved type uses an annular piston which is sealed against the brake housing by means of seals. Such a brake comprises a pressure chamber for supplying a pressure medium to apply the required relieve pressure. Such a braking apparatus is compact in size and uses a large brake piston which is suitable for a low relieve pressure. However, it is a disadvantage of that known brake apparatus, that the low amount of space required has to be achieved by means of a spring element mounted in the brake housing, a spring element which acts upon the brake piston. This single spring element has inherently a steep spring characteristic, i.e. for small movements of the spring a large change of the force is obtained. So as to provide for the required defined breaking forces, the components of that known brake apparatus have to have precise dimensions, a fact, which leads to high manufacturing and assembling costs.
It is an object of the present invention to overcome one or more of the problems of the prior art. It is another object of the present invention to provide a braking apparatus of compact design, particularly in axial direction, without having the disadvantages of close axial tolerances. In accordance with a further object of the invention the disadvantages which are due to a steep spring characteristic are to be avoided.
Additional brake apparatus of the prior art are shown in British patents 2,131,005 and 884,501 and also in German laid open applications 3,211,366 and 1,418,599.